docs: add guest image command inventory - #685

… v0.5.1/v0.5.3 pages

Follow-ups from the Phala Cloud pre-launch v0.0.17 incident
(Phala-Network/phala-cloud-monorepo#1936), where three fleet-wide guest
userland traits were confirmed on real CVMs and in the pinned poky
defconfig:

- BusyBox 1.36.1 is built from the same kirkstone defconfig on every
  0.5.x image, with sub-features trimmed: no 'head -c'
  (CONFIG_FEATURE_FANCY_HEAD), no 'dd ibs=/obs=/conv='
  (CONFIG_FEATURE_DD_IBS_OBS), no chpasswd/cryptpw/mkpasswd applets,
  and busybox passwd has no --stdin. Add a BusyBox Option Caveats
  section with workarounds ('dd bs=1 count=N') and per-page pointers.
- Non-interactive password setting only works by writing an
  'openssl passwd -6' hash into /etc/shadow; openssl ships in every
  image via ca-certificates. Add a Password and Account Management
  section, including the locked-account warning: dev-image sshd is
  OpenSSH built without PAM, so 'passwd -l' denies ALL authentication
  including public keys.
- Document the two dev-image traits behind the incident (PAM-less
  sshd, debug-tweaks empty root password).

Also:
- Add v0.5.1 and v0.5.3 pages (both still deployed) derived from build
  recipes diffed against the verified v0.5.4 inventory: no pigz (gzip/
  gunzip/zcat are BusyBox applets), v0.5.1 keeps qemu-ga and lacks
  fuse3.
- Extend every version page's not-present list with chage/chpasswd/
  cryptpw/mkpasswd/usermod.
- Note the v0.5.11+ build-tree relocation into os/yocto.